The present invention is directed to a relatively simple and inexpensive method for detecting the presence of antibiotics in milk.
Mastitis is probably the most frequently observed disease state of dairy cows. Treatment of mastitis in dairy cows usually is carried out by either injection or udder infusion of antibiotic preparations, most notably penicillin. An undesirable consequence is that small amounts of antibiotics are found in some milk obtained from treated animals when collected from the farm. Persistence of these antibiotics throughout processing causes failure of culture organisms and leaves residual antibiotics in consumer products. Allergic reactions to antibiotics and loss of sensitivity of the general population to antibiotics, caused by continual long term exposure to low doses, are realities which must be faced.
The presence of penicillin in the milk supply is thus a major concern because it constitutes a public health hazard. Also, such contaminated milk is not suitable for manufacture of cultured dairy products. Most fluid milk is now transported in bulk tank trucks so contaminated milk from a single cow can subsequently contaminate the milk from many herds in a large bulk tank truck. Thus, a rapid and simple test which could be performed by the hauler or farmer prior to loading the herd milk into the bulk tank truck could result in a great savings.
Present methods for detecting antibiotics generally require microbial assays and, hence, considerable time and laboratory facilities are necessary. Present chemical tests do not have sufficient sensitivity to detect the minimum tolerable levels of antibiotic concentration.
A radioimmunoassay technique which utilizes the competition between radio-labelled antibiotic and sample antibiotic for antibody would be very sensitive; however, this method would require trained personnel and expensive equipment.
Thus, there has not been available a fast, acceptable test for antibiotics which can be routinely used by farm or dairy plant workers. As noted, the limiting factors in the available tests have been sensitivity to the low levels of antibiotics which must be detected and the time required to conduct the tests. Where these two factors are overcome, expense of the test and equipment required become prohibitive, especially for on the farm use.
Accordingly, and as a primary object of the present invention, there is provided herein a test which overcomes the foregoing problems.
A further object of the present invention is to provide a test designed for detection or measurement of benzylpenicillin and other antibiotics which may be found in milk.
It is yet another object of our invention to provide a method for the detection of all forms of penicillin at very low concentrations in accordance with the following guidelines:
1. The test should be sensitive to 0.01 units/ml;
2. Time required for a single test should not exceed about 10 minutes;
3. Untrained personnel should be capable of performing the test. (The present test has been designed specifically for use at the farm by the farmers themselves and by milk truck drivers.);
4. The cost per test should be as inexpensive as possible.
With prior procedures, these objectives could not be attained since (a) required incubation times of the binding partners were excessively long; (b) expensive, specialized equipment was required; and (c) trained laboratory personnel were required to perform the test.
These and other objects of the invention will be more apparent from the discussion below.